A practical, no-nonsense sewing guide for home sewists and DIY crafters working with nylon-spandex fabric, covering tools, machine settings, cutting, stitching, finishing, and the best projects to start with.
Nylon-spandex has a reputation in the sewing community for being tricky. Wavy seams. Skipped stitches. Fabric that slides everywhere under the presser foot. Hems that look professional from the front and chaotic from the back. Sound familiar?
The good news is that almost every one of those problems has a specific, fixable cause. Nylon-spandex is not a forgiving fabric if you approach it the same way you would cotton, but once you understand what it needs, it becomes one of the most rewarding materials to work with. The finished results, leggings that hold their shape perfectly, swimwear that fits like it was custom made, a sports bra that actually stays put, are hard to achieve with anything else.
This guide is written specifically for home sewists and DIY crafters. It covers everything from choosing the right fabric to finishing professional hems without a serger. For the full background on what nylon-spandex is and why it performs the way it does, our complete nylon-spandex fabric guide covers that ground. This article is focused entirely on getting it onto your machine and out as something you are proud of.
Is Nylon-Spandex Right for Your Project?
Evaluating whether nylon spandex fabric is suitable for a specific sewing or apparel project.
Before buying a yard of anything, it helps to confirm that nylon-spandex is actually the right call for what you are making. It is not the right choice for every project, and knowing this upfront saves frustration.
Nylon-Spandex Works Well For:
- Leggings, yoga pants, and fitted activewear
- Sports bras and athletic tops
- Swimwear, bikinis, and one-pieces
- Dancewear, leotards, and gymnastics outfits
- Fitted bodysuits and lingerie
- Compression garments and shapewear
- Rash guards and performance tights
- Athleisure pieces where comfort and shape retention both matter
Nylon-Spandex Is Not Ideal For:
- Structured garments that need to hold a shape without the body inside
- Outerwear and bags where durability under abrasion is the priority (use plain nylon instead)
- Projects that will be pressed or ironed frequently at anything above the lowest heat setting
- Beginners who have never sewn stretch fabric of any kind
If you are completely new to sewing: Nylon-spandex is not the place to start. It requires specific tools, specific techniques, and a tolerance for test seams before the real thing. Get comfortable with a jersey knit or cotton-spandex project first. Those fabrics are more forgiving, and the skills transfer directly to nylon-spandex once you are ready.
Choosing the Right Nylon-Spandex for Your Project
Selecting the right nylon spandex fabric depends on the intended garment and performance requirements.
Walking into a fabric store or browsing online and seeing “nylon-spandex” tells you almost nothing. The blend ratio, GSM weight, knit construction, and any finish treatments will all determine whether the fabric works for your specific project. Here is how to choose.
| Project Type | Blend Ratio | GSM Range | Key Features to Ask For |
|---|---|---|---|
| Yoga pants and leggings | 87/13 or 82/18 | 200-250 GSM | Opaque when stretched, buttery soft hand, four-way stretch |
| Swimwear (recreational) | 80/20 | 180-220 GSM | DWR or chlorine-resistant finish, wet opacity, UPF treatment |
| Competitive swimwear | 80/20 with Xtra Life LYCRA | 180-200 GSM | Certified chlorine resistance, fast-dry, shape retention |
| Sports bras | 82/18 to 87/13 | 180-230 GSM | Four-way stretch, moisture-wicking finish, opacity |
| Dancewear and leotards | 80/20 to 75/25 | 150-200 GSM | High stretch, bright color, smooth surface for print clarity |
| Fitted bodysuits and lingerie | 87/13 to 92/8 | 140-180 GSM | Soft, smooth, fine gauge, good recovery |
| Rash guards | 90/10 | 180-220 GSM | UPF 50+ treatment, chlorine resistance |
| Compression tights | 80/20 | 220-280 GSM | Graduated compression, high recovery, opaque |
Checking Opacity Before You Buy
For leggings and swimwear especially, opacity matters a great deal. The fastest way to check a sample is the squat test: stretch the fabric across your hand or against a contrasting surface and see what shows through. Do this in both directions. Do this in the color you plan to use, because pale colors and white are significantly more transparent than dark colors at the same GSM.
As a general rule, anything under 180 GSM in a pale color needs checking very carefully. Anything under 160 GSM in white or nude should be lined unless the design specifically relies on sheerness.
Not sure which fabric weight to choose?
The Fabric Weight Calculator helps you compare fabric weights and understand what different GSM ranges feel like in practice.
Understanding Stretch Percentage
This is the single most important concept for sewing nylon-spandex successfully, and it is also the thing most beginners skip. If your fabric does not have enough stretch for the pattern you are using, the garment will be too tight or may tear when put on. If it has too much stretch, the garment bags out and loses its shape.
How to Measure Stretch Percentage
Cut a test strip
Cut a strip of your fabric 5 inches long in the direction of greatest stretch (usually across the grain, from selvage to selvage). Knit fabrics stretch more across the grain than along it.
Stretch it against a ruler
Hold the strip next to a ruler and stretch it firmly in the cross-grain direction until it resists. Note how far it extends beyond the original 5 inches.
Calculate the percentage
Divide the extra length by the original length. If 5 inches stretches to 8 inches, that is 3 extra inches, which equals 60% stretch (3 divided by 5 = 0.6). Most activewear patterns need 50-75% stretch. Swimwear patterns typically need 75% or more.
Test recovery
Release the strip and check that it returns fully to its original 5 inches. Fabric that does not recover fully will bag out after wearing. Poor recovery is a quality issue that no amount of sewing skill can fix.
Understanding Negative Ease
Most stretch garment patterns are designed with negative ease. This means the finished garment measurements are intentionally smaller than your body measurements. The fabric stretches to fit. A leggings pattern sized for a 36-inch hip might have a finished hip measurement of only 30 inches, relying on the fabric to provide the remaining 6 inches through stretch.
This is why checking stretch percentage against your pattern requirements is not optional. A pattern that calls for 75% stretch will not work correctly in a fabric with only 50% stretch. The garment will be too tight to get on, or will apply uncomfortable compression if you do manage it.[1]
Quick rule of thumb: Most activewear leggings patterns need at least 50-60% stretch. Swimwear patterns need at least 75%. Compression garments need 75-100%+. Always read the stretch requirement printed on or in your pattern before selecting fabric, and test your actual fabric, not just the label description.
Tools You Need Before You Start
Essential sewing tools for handling nylon spandex fabric successfully.
The right tools make nylon-spandex significantly easier to sew. Getting set up properly before you start is the most efficient investment of time you can make on any stretch fabric project.
The single most important tool choice. A stretch needle (Schmetz brand is the benchmark) has a deeper scarf and special tip that slides between knit fibers rather than piercing them. This prevents the skipped stitches that plague nylon-spandex sewing. Size 75/11 for lightweight fabric, 80/12 for most projects, 90/14 for heavier fabric. Change your needle at the start of every project.
The standard choice for nylon-spandex. Polyester thread has slight stretch, resists chlorine and UV, and is strong enough for the stress stretch seams experience. Avoid cotton thread entirely; it has no give and will snap when the seam is stretched. Gutermann Maraflex is a popular stretch-specific polyester thread worth having for swimwear and high-stress seams.
For serger loopers specifically. Wooly nylon thread (wound by hand onto serger bobbin cones) is incredibly soft and stretchy, producing seam allowances that are comfortable against the skin and never pop. If you serge swimwear or lingerie, wooly nylon in the loopers makes a noticeable difference to the finished quality.
Feeds both layers of fabric at the same rate rather than letting the presser foot drag the top layer while the feed dogs move the bottom. This is one of the most effective fixes for uneven or wavy seams on nylon-spandex. If you do not have a serger, a walking foot on your regular machine gets you surprisingly good results.
The non-stick sole glides over nylon-spandex’s slippery surface without dragging. Particularly useful on very fine or slick fabrics where a standard foot sticks and causes uneven feeding. A good alternative to a walking foot for lightweight nylon-spandex.
Far more accurate than scissors for stretch fabric. A sharp rotary cutter cuts cleanly through nylon-spandex without shifting or dragging the fabric. Use a fresh blade; a dull blade causes the fabric to move as you cut, producing uneven edges.
Use instead of pins wherever possible. Pins distort stretch fabric and can leave holes that do not close up. Pattern weights (or improvised alternatives like soup cans or heavy rulers) hold pattern pieces flat without any risk of distortion.
Where you need to hold fabric layers together along a seam before sewing, clips grip without piercing. Much better than pins on any stretch fabric. Ball-headed pins can be used sparingly within the seam allowance if needed, but keep them well inside the allowance and remove before the needle reaches them.
A secret weapon for stabilizing curved seams and necklines on swimwear and bodysuits. Clear elastic sewn into a seam prevents it from stretching out over time without adding bulk. Standard for swimwear waistbands, leg openings, and necklines.
For swimwear projects specifically, use rubber or cotton-covered elastic rather than standard knit elastic. Rubber elastic resists chlorine and saltwater, recovers better than standard elastic after repeated stretching, and lasts far longer in swimwear applications.
Do You Need a Serger?
No, but it helps enormously. A regular sewing machine with a zigzag stitch and a stretch needle will produce functional, durable seams on nylon-spandex. A serger produces faster, neater, more professional seams in a single pass. For activewear you will wear to the gym, a regular machine is fine. For swimwear or any garment where seam comfort against the skin matters, a serger truly earns its place.
If you do not have a serger, a twin needle on a regular machine produces a professional-looking stretchy hem that mimics the coverstitch finish on ready-to-wear activewear.
Not sure which needle size to use?
The Needle and Fabric Compatibility Chart matches needle types and sizes to fabric weight and type.
Preparing Nylon-Spandex Before Cutting
Should You Pre-Wash Nylon-Spandex?
For most nylon-spandex, a pre-wash before cutting is a good idea, even though nylon itself does not shrink significantly. Here is why:
- Manufacturing sizing (a finish applied during production to make the fabric easier to handle) can affect how the fabric behaves on the machine and how it accepts dye. Washing removes it.
- Any slight relaxation that does happen is better to get out before you cut your pattern pieces than after you have assembled the garment.
- For swimwear fabric specifically, a pre-wash ensures the chlorine-resistant finish has fully bonded before the first swim test.
Wash in cold water on a gentle cycle. Air dry flat. Do not tumble dry even at this stage, as heat degrades the spandex component.
Letting the Fabric Relax
After washing and drying, lay the fabric flat on your cutting surface for at least an hour before cutting. Nylon-spandex that has been folded or rolled can have a “memory” of that fold, and cutting while the fabric is still holding tension from its storage position will result in pattern pieces that shift once the fabric relaxes. A flat resting period prevents this.
Handling Static
Nylon-spandex builds up static charge, especially in dry conditions. Static makes layers cling together, stick to cutting mats, and shift during cutting. A light mist of water from a spray bottle across the surface before you start, or a quick wipe with a damp cloth, reduces static enough to make the fabric manageable. Grounding yourself by touching a metal surface before handling the fabric also helps.
The Test Seam Rule
Before cutting a single pattern piece, sew a test seam on a scrap of the actual fabric you are using. Use the same needle, thread, stitch, and settings you plan to use for the project. Stretch the test seam firmly after sewing. If the stitches pop, the stitch you are using has no stretch. If the seam puckers, your tension needs adjusting. Fix the problem on the scrap, then cut your fabric. This step prevents the most common and most frustrating nylon-spandex sewing disasters.
Cutting Nylon-Spandex Accurately
Essential cutting techniques for achieving precise results when working with nylon spandex fabric.
Cutting is where many stretch fabric projects go wrong before a single stitch is made. Nylon-spandex is slippery, it stretches, and it shifts. Here is how to cut it cleanly.
Lay flat on a non-slip surface
Use your cutting mat. If the fabric slides off the edge of the mat or table, place a piece of flannel or a non-slip mat underneath to add grip. Fabric that overhangs the table edge will stretch under its own weight and distort your cuts.
Cut one layer at a time for slippery fabric
Folding nylon-spandex in half and cutting both layers is efficient but risky. The layers shift against each other. For precise cuts, especially on curves and diagonal lines, cut single layers. Use a mirror-image cut or trace pattern pieces in reverse for pieces that need to be cut as pairs.
Orient the greatest stretch across the body
Knit fabrics stretch more in one direction than the other. The direction of greatest stretch should always go around the body (horizontally), not up and down. Pull the fabric in both directions to identify which direction gives more. Most patterns mark this on the pattern piece with a grainline arrow, align this with the lengthwise grain of the fabric, which means the cross-grain (more stretch) goes horizontal on the body.
Use pattern weights and a rotary cutter
Hold pattern pieces down with pattern weights. Use a sharp rotary cutter for long edges and a sharp pair of fabric scissors for curves and tight spots. Change your rotary blade if you notice it dragging rather than cutting cleanly; a dull blade moves the fabric as it cuts.
Mark carefully without stretching
Use tailor’s chalk, a fabric-safe marker, or small clips at notch points. Avoid marking methods that require heat to remove. If you need to mark the wrong side of the fabric, a sliver of chalk or a water-soluble pen works well. Always test your marking tool on a scrap first, because some markers bleed through fine nylon-spandex.
Keep seam allowances generous
Use at least 1 cm (3/8 inch) seam allowances on nylon-spandex, and prefer 1.5 cm (5/8 inch) where possible. Stretch fabric seams experience real stress in use, and larger allowances give more fabric for the stitch to work with. Many activewear patterns already include narrow seam allowances, check your pattern and adjust if needed.
Do not cut off-grain: Cutting nylon-spandex off-grain (not aligned with the fabric’s grid structure) can cause the finished garment to twist, spiral, or look misshapen after washing. This is especially pronounced in leggings and tights. Take the extra time to align your pattern pieces correctly before cutting.
Machine Settings for Nylon-Spandex
Correct machine settings help create smooth, durable seams in nylon spandex garments.
Getting your machine dialed in before starting a project prevents the most common problems. Every machine is slightly different, so these are reliable starting points to adjust from based on your test seam results.
| Setting | Recommended Starting Point | Why It Matters |
|---|---|---|
| Needle | Stretch needle, size 75/11 to 80/12 for most fabrics. 90/14 for heavier weights. | The most impactful single change you can make. Stretch needles prevent skipped stitches by design. Replace at the start of every project. |
| Thread | 100% polyester in needle and bobbin. Wooly nylon in serger loopers. | Polyester thread stretches slightly with the fabric. Cotton thread has no stretch and will break under tension. |
| Stitch | Narrow zigzag (1.0-1.5mm wide, 2.5mm long) or your machine’s built-in stretch stitch. | Stretch stitches stretch with the fabric. A straight stitch has no give and seams will pop under wear. |
| Stitch Length | 2.0mm to 2.5mm | Slightly shorter than standard for wovens. Too short and you create too many perforations along the seam; too long and the seam may not hold under stretch. |
| Thread Tension | Slightly lower than your machine’s default | Looser tension allows the thread to give when the seam is stretched. Too-tight tension causes puckering and seam breakage under stretch. |
| Presser Foot Pressure | Slightly reduced from standard | Too much pressure stretches the top layer of fabric as it feeds through, causing wavy seams. Reducing it is often the fastest fix for waviness. |
| Presser Foot | Walking foot as default. Teflon or roller foot for very slippery fabric. | A standard foot can drag the top layer while the feed dogs move the bottom, causing uneven feeding and twisted seams. |
| Sewing Speed | Medium. Never rush. | Rushing causes the fabric to shift under the foot. Sew steadily, especially around curves and at the start and end of seams. |
The golden rule: Test every setting on a scrap of your actual fabric before cutting your pattern pieces. Sew a 6-inch test seam, then stretch it firmly. If stitches pop, change to a stretch stitch. If the seam puckers, reduce tension. If the fabric shifts, try the walking foot or reduce presser foot pressure. Every machine and every fabric combination behaves slightly differently.
For general guidance on maintaining your machine for stretch fabric sewing, our sewing machine care guide and guide to sewing machine stitches are useful references.
Which Stitches to Use
The most common reason nylon-spandex seams fail is using a straight stitch. A straight stitch has no stretch. When the seam is pulled, the thread breaks rather than giving. Here are the stitches that actually work, in order of preference.
For a Regular Sewing Machine
| Stitch | Settings | Best For |
|---|---|---|
| Narrow Zigzag | Width 1.0-1.5mm, length 2.5mm | The most reliable stretch stitch for most home machines. Stretches with the seam, strong, and easy to unpick if needed. Good for all nylon-spandex seams. |
| Built-in Stretch Stitch | Machine default, consult manual | Many modern machines have a dedicated stretch stitch (sometimes shown as a lightning bolt symbol). Uses a forward-back-forward pattern that creates a very strong stretchy seam. Harder to unpick. |
| Three-Step Zigzag | Width 3-4mm, length 3mm | Wider coverage. Good for finishing edges and for high-stress seams in compression garments and swimwear. |
| Twin Needle Stitch | Twin needle 2mm or 4mm width, standard straight stitch setting | Creates two parallel rows of straight stitch on the face and a zigzag on the wrong side. The standard for professional-looking stretchy hems on leggings and activewear. |
For a Serger (Overlocker)
A three or four-thread overlock stitch trims the seam allowance, encloses the edge, and creates a stretchy seam in one pass. This is the standard for activewear and swimwear construction. Use polyester thread in the needles and wooly nylon in the loopers for the softest, stretchiest result against the skin.
A flatlock stitch on a serger creates a flat, smooth seam with no bulk sitting against the skin, ideal for yoga wear and compression garments where seam lumpiness would be noticeable through the thin fabric.
The Stitch You Must Never Use
Do not use a standard straight stitch for the main seams of any garment made from nylon-spandex. It will look fine on the machine, and it may even survive a few wears. But the first time someone puts the garment on and stretches it firmly at a seam, the stitch will pop. The only exception is when using a straight stitch as a stay stitch (a single row of stitching just inside the seam allowance to stabilize a curved edge before sewing), where stretch resistance is actually what you want.
For a broader look at how different stitches work on stretch fabric, our guide to sewing machine stitches covers the full range.[2]
Sewing Techniques That Work
Practical sewing techniques for achieving smooth and professional nylon spandex results.
Preventing Wavy Seams
Wavy, “lettuce-edged” seams are the most common complaint when sewing nylon-spandex. They happen when the fabric stretches as it passes through the machine. There are three causes and three fixes:
- Cause 1: Presser foot pressure too high. The foot compresses and drags the fabric. Fix: reduce presser foot pressure on your machine. This is often the fastest solution.
- Cause 2: Thread tension too tight. The thread pulls the fabric inward as it stitches. Fix: reduce upper thread tension slightly from your default setting.
- Cause 3: Pulling or holding the fabric as you sew. Even a light hand on the fabric behind or in front of the needle introduces stretch. Fix: let the feed dogs do all the work. Guide the fabric very lightly, do not pull.
Starting Seams Without Puckering
Nylon-spandex can get sucked into the needle plate at the start of a seam, especially if you are working on a small or lightweight piece. To prevent this, begin your seam on a fabric scrap (called a leader) and transition onto your actual fabric as you sew. The leader gives the feed dogs something to grip before they reach your project piece. Alternatively, hold both thread tails firmly behind the presser foot for the first few stitches.
Sewing Curves
On curved seams such as the crotch seam of leggings or the leg opening of a swimsuit, slow down significantly and take your time. Use your needle-down function if your machine has one. On tight curves, stop every few stitches, leave the needle down, and lift the presser foot briefly to reposition the fabric. Rushing curves on stretch fabric produces diagonal pulls and distorted seams.
Using Tissue Paper for Very Slippery Fabric
For very fine or slippery nylon-spandex, place a strip of tissue paper under the fabric as you sew along a seam. The paper gives the feed dogs something stable to grip. Tear the paper away after sewing. This technique is also useful when you need to sew very close to the edge of a piece without the fabric slipping away from the needle.
Applying Clear Elastic
Clear elastic is used to stabilize seams in swimwear and bodysuits, particularly at leg openings, waistbands, and necklines. Cut clear elastic to your body measurement (not the pattern piece measurement), stretch it slightly as you sew it to the wrong side of the seam allowance using a zigzag stitch. When the seam is folded and sewn, the elastic prevents the edge from stretching out over time while still allowing the garment to stretch enough to put on and take off.
Seam Finishing, Hems, and Elastic
Sewing machine applying seam finishing techniques to improve fabric durability and appearance.
Seam Finishing Options
Nylon-spandex does not fray the way woven fabrics do, which is one of its practical advantages. However, raw edges can roll and curl, which can be uncomfortable against the skin. Here are the main finishing options:
- Serged edge: The cleanest and most professional finish. A 3-thread overlock cuts and encloses the edge in one pass.
- Zigzag stitch: A wide zigzag along the raw edge stops the curl without requiring a serger. Trim close after stitching.
- Leave it raw: On enclosed seams where both layers are folded inward, raw edges are acceptable and do not cause problems. Many commercial activewear garments do this on interior seams.
Hemming Nylon-Spandex
Hems on nylon-spandex garments need to stretch with the fabric or they will pop or cause the edge to pucker when worn.
- Twin needle hem: The standard for home sewists. Fold the hem up, press very lightly or finger-press, and sew with a twin needle. Two rows of stitch on the face, one zigzag on the back, all in one pass. This is what the hems on most commercial leggings look like.
- Coverstitch: If you have a coverstitch machine (a machine dedicated to stretch hems), this produces the most professional result. Not essential for most home projects but worth the investment if you sew a lot of activewear.
- Serger rolled hem: A narrow serged edge that rolls the fabric under in a single pass. Works well on fine nylon-spandex fabric for a neat, compact hem.
- Zigzag hem: A simple zigzag stitch through a single fold works on heavier fabric where the edge is less likely to show through.
Applying Elastic
Nylon-spandex garments typically use elastic at waistbands, leg openings, and cuffs. There are two main methods:
Cased elastic (threaded through a channel): Sew a casing (a folded channel) at the waistband, thread elastic through, and join the ends. Works well for relaxed-fit waistbands. Use a stretch stitch when sewing the casing so it can expand with the elastic.
Applied elastic (sewn directly): Divide the elastic and the garment opening into quarters. Match the quarter marks. Stretch the elastic to meet each quarter mark as you zigzag or serge it to the fabric. This method gives a cleaner result for fitted waistbands and leg openings.
For swimwear, use rubber or latex-core elastic (sold as swimwear elastic) rather than standard knit elastic. Standard elastic degrades in chlorine and saltwater; swimwear elastic holds its recovery through repeated exposure. This is one of the details that separates a swimsuit that lasts one season from one that lasts several years.
For more on seam finishing approaches, our guides to French seams and flat-felled seams cover related construction techniques that complement stretch fabric work.[3]
Pressing Nylon-Spandex Safely
Proper pressing techniques help protect nylon spandex fabrics from heat damage.
Both nylon and spandex are heat-sensitive. Nylon melts at relatively low temperatures. Spandex degrades and permanently loses elasticity when overheated. Pressing mistakes on nylon-spandex are irreversible.
Rules for Pressing
- Always use a pressing cloth between the iron and the fabric. A piece of cotton muslin works perfectly.
- Set your iron to the lowest heat setting, labeled Synthetic or equivalent.
- Never use steam directly on nylon-spandex. Steam at sewing temperatures can distort the fabric or cause water spotting.
- Use brief, light contact only. Do not hold the iron in place.
- Test on a scrap first every single time. Different blends have different heat tolerances.
- Let the fabric cool completely before moving or sewing over pressed areas.
Finger Pressing: The Safer Alternative
For most seam work on nylon-spandex, finger pressing is safer and often more effective than ironing. Run your thumb and forefinger firmly along a seam allowance to open it flat. A seam roller (a small smooth roller on a handle) does the same job with more pressure. For most activewear seam allowances, this is all you need.
When You Cannot Get a Crease
Nylon-spandex often resists creasing. For hems, this means you may need to use clips or pins to hold the fold in place while you sew rather than relying on a pressed crease to keep things flat. Building this into your workflow rather than fighting it produces better results.
Troubleshooting Common Problems
Seams are popping or breaking when stretched
You are using a straight stitch or a stitch with insufficient stretch. Switch to a narrow zigzag (width 1.0-1.5mm, length 2.5mm) or your machine’s stretch stitch. Test the seam by stretching it firmly before it goes into the garment.
Seams are puckering or wavy
Three possible causes: presser foot pressure too high (reduce it), thread tension too tight (loosen it slightly), or you are pulling the fabric as you sew (stop, let the machine feed the fabric on its own). Address one variable at a time on a scrap piece until the seam lies flat.
Skipped stitches
Change the needle first. Skipped stitches on stretch fabric are almost always a needle issue, either the wrong type (use a stretch or ballpoint needle) or a needle that is past its useful life. If changing the needle does not fix it, check that the needle is fully inserted into the clamp and re-thread the machine completely.
Fabric is sucked into the needle plate at the start of a seam
Begin on a fabric leader (a scrap piece), then transition onto your actual fabric. Or use a straight-stitch needle plate if your machine has one. Holding both thread tails behind the presser foot for the first few stitches also prevents this.
The top layer of fabric is shifting ahead of the bottom layer
Switch to a walking foot. Alternatively, try placing tissue paper between the layers. Reducing presser foot pressure also helps. Check that you are not accidentally pulling or holding the fabric, which amplifies any differential feeding.
Twin needle hem has tunnelling (fabric bunching between the needle rows)
Loosen the upper thread tension. Reduce presser foot pressure. Try a slightly wider twin needle (4mm instead of 2mm). Use a walking foot. Tunnelling on twin needle hems is a tension and pressure issue, adjust one variable at a time on a scrap until the hem lies flat.
Thread keeps breaking
Check the needle; a bent or blunt needle is the most common cause. Also check that tension is not too tight and that you are not using cotton thread. If the needle and thread are correct, check that the thread path is seated correctly in the upper tension discs.
Garment twists or spirals after washing
The fabric was cut off-grain. The cross-grain of the fabric must be oriented horizontally on the body. Re-examine how you positioned your pattern pieces and whether you correctly identified the direction of greatest stretch before cutting.
For broader sewing machine diagnosis, our sewing machine troubleshooting guide covers most common mechanical issues in detail.
Best Projects by Skill Level
Here are project ideas organized by skill level, with notes on why each works well as a starting point or next step for nylon-spandex sewing.
You have sewn before and are comfortable with basic seams, but stretch fabric is new to you.
- Scrunchies and hair ties
- Stretch headband
- Simple tube skirt (no waistband)
- Basic bike shorts with elastic waistband
- Swim cover-up (loose fit, minimal shaping)
You are comfortable with stretch fabric basics and ready for fitted construction and curved seams.
- Leggings or yoga pants
- Sports bra (light to medium support)
- Simple one-piece swimsuit
- Fitted tank top or crop top
- Fitted bodysuit
- Rash guard
You are confident with nylon-spandex construction and ready for complex shaping, lining, and hardware.
- Underwire swimsuit or bikini
- High-support sports bra with boning
- Compression leggings with panels
- Dance costume or gymnastics leotard
- Lined swim shorts with pockets
Project Spotlights
Leggings: The Best First Real Project
Leggings are the ideal introductory nylon-spandex project because they are relatively simple in construction (four seam pieces, a waistband, and two hems), the fit is forgiving within a range, and the skills you learn transfer directly to every other stretch garment. Use an 87/13 nylon-spandex in 200-230 GSM, a stretch needle, a narrow zigzag, and a walking foot. A good free leggings pattern from a reputable pattern designer is worth printing out rather than drafting your own for a first attempt.
Swimwear: The Most Satisfying Advanced Project
Sewing your own swimwear is one of the most rewarding DIY garment projects because fit is so personal and off-the-rack swimwear fits so inconsistently. The key steps beyond standard nylon-spandex technique are using swimwear-grade fabric (chlorine-resistant, UPF-treated), swimwear elastic at all openings, and clear elastic at the leg openings to prevent them from sagging. Seamwork’s guide to sewing swimwear is one of the most practical resources available for home sewists attempting swimwear for the first time.[3]
For beginner-friendly sewing project ideas across fabric types, our easy sewing projects for beginners guide is a good starting point, and our beginner-friendly sewing patterns page has pattern recommendations that include stretch fabric options.
Frequently Asked Questions
Can I sew nylon-spandex on a regular home sewing machine?
Yes. A regular home machine with a stretch or ballpoint needle, polyester thread, and a zigzag stitch handles nylon-spandex well. You do not need a serger, although a serger produces faster, neater seams. A walking foot attachment makes a significant difference to seam quality and is a worthwhile addition for any home machine used to sew stretch fabrics.
What needle should I use for nylon-spandex?
Use a stretch needle (Schmetz Stretch is the most recommended) or a ballpoint/jersey needle. Size 75/11 for lightweight fabric, 80/12 for most standard activewear and swimwear weights, 90/14 for heavier compression fabrics. Change the needle at the start of every project. A blunt or damaged needle causes skipped stitches on stretch fabric more than any other issue.
What stitch should I use for nylon-spandex seams?
A narrow zigzag stitch (width 1.0-1.5mm, length 2.5mm) is the most reliable choice for home machines. Your machine’s built-in stretch stitch (often shown as a lightning bolt or triple-stitch symbol) is also excellent. Never use a standard straight stitch for main seams; it has no stretch and seams will break under wear.
Why do my seams keep popping on nylon-spandex?
Almost always because of a straight stitch or a stitch without adequate stretch. Switch to a narrow zigzag or built-in stretch stitch. After sewing, always do a firm stretch test on a scrap seam before using those settings on your actual project. A seam that pops during testing saves you from one that pops during wearing.
Why are my nylon-spandex seams wavy?
Wavy seams have three common causes: presser foot pressure too high, thread tension too tight, or pulling the fabric as you sew. Reduce presser foot pressure first; this is the most frequent cause and the easiest fix. Then reduce thread tension slightly. Make sure you are guiding the fabric very lightly and letting the feed dogs do the work.
Do I need to pre-wash nylon-spandex before sewing?
Yes, for most projects. A cold gentle pre-wash removes manufacturing sizing, allows any minimal relaxation to happen before you cut your pattern pieces, and pre-conditions the fabric for how it will behave in use. Air dry flat, never tumble dry, even at this stage. Skipping pre-washing on nylon-spandex swimwear can mean the first real wash changes the fabric’s behavior after the garment is already made.
How do I hem nylon-spandex without a serger?
A twin needle on a regular sewing machine produces a professional-looking hem with two rows of stitch on the face and a zigzag on the wrong side. Fold and finger-press the hem allowance, then sew with the twin needle from the right side. If the hem tunnels (fabric bunches between the needle rows), reduce upper tension and presser foot pressure. A simple narrow zigzag through a single fold also works on heavier fabrics.
Can I iron nylon-spandex?
With strict precautions only. Use the lowest heat setting, always place a pressing cloth between the iron and the fabric, never use steam directly, and test on a scrap first. Nylon melts and spandex degrades at surprisingly low temperatures. Finger pressing (running your fingers firmly along a seam to flatten it) is the safer choice for most seam work on nylon-spandex.
What elastic should I use for nylon-spandex swimwear?
Use rubber or latex-core swimwear elastic, not standard knit or braided elastic. Swimwear elastic is specifically designed to resist chlorine and saltwater, which standard elastic cannot withstand without degrading over time. Apply it to leg openings and waistbands by dividing both the elastic and the opening into quarters and stretching the elastic to match as you sew with a zigzag stitch.
How do I know if my fabric has enough stretch for a pattern?
Measure the stretch percentage: cut a 5-inch strip in the cross-grain direction and stretch it until it resists. Divide the extra length by 5. Most activewear patterns need 50-75% stretch. Swimwear patterns typically need 75% or more. Always check the stretch requirement on your pattern and test your actual fabric, not just the supplier’s description.
Conclusion
Nylon-spandex has a learning curve, but the problems most people encounter come from a small set of fixable causes. The wrong needle causes skipped stitches. The wrong stitch causes seam breakage. Too much presser foot pressure causes wavy seams. Cutting off-grain causes twisting. Most of these are problems you can identify and fix on a test scrap before your actual project is ever touched.
Once you have the setup right, nylon-spandex is a pleasure to work with. It moves beautifully on the machine, the seams are strong, and the finished garments are things you will actually wear rather than projects that sit folded in a drawer because the fit was not quite right.
Key Takeaways
- Use a stretch or ballpoint needle. This single change fixes the majority of skipped stitch problems. Change it at the start of every project.
- Use polyester thread, never cotton. Cotton has no stretch and will break under the stress of stretch seams.
- Use a stretch stitch or narrow zigzag. Standard straight stitches have no stretch and seams will pop under wear.
- Test before cutting. Sew a test seam on a scrap of your actual fabric and stretch it firmly. Fix problems there, not on your finished project.
- Reduce presser foot pressure if seams are wavy. This is the most common cause of waviness and the quickest fix.
- Cut single layers for accuracy on slippery or very stretchy fabric. Orient the greatest stretch horizontally (across the body).
- Measure stretch percentage before buying fabric for a pattern with a specific stretch requirement. Do not trust the label alone.
- Use swimwear elastic for swimwear. Standard elastic degrades in chlorine and saltwater. Swimwear-specific elastic does not.
- Never apply heat directly. Always use a pressing cloth at the lowest iron setting. Finger pressing is safer for most seam work.
This is the second part in our nylon-spandex series. The main nylon-spandex guide covers the full overview including properties, blend ratios, comparisons, and sustainability. The other articles in the series are tailored for fashion and apparel students and small business owners sourcing and selling nylon-spandex products.
References
- Spandex Palace. (2025). How Much Stretch Do You Really Need? A Guide to Perfect Projects. spandexpalace.com
- EOVEA Fabric. (2026). How to Sew Spandex Fabric: Complete Beginner’s Guide. eoveafabric.com
- Seamwork. (2025). 5 Secrets for Sewing a Swimsuit That Fits, Flatters, and Doesn’t Budge. seamwork.com
- Melly Sews. (2025). Sewing Spandex: Tips for Working with Lycra and Elastane. mellysews.com
Disclaimer: The sewing techniques and machine settings described in this article are general guidance for home sewists working with standard domestic sewing machines. Results vary depending on your specific machine, fabric, thread, and experience level. Always test on scrap fabric before cutting into your project. Clothing Digest is not responsible for any outcomes resulting from the application of guidance provided in this article.
